Method of making insulating material.



' No. 687,532. Patented Nov. 26, [90L C. W. JEFFERSON. METHOD OF MAKING INSULATING MATERIAL.

(Application filed Feb. 7, 1901.)

(No' Model.)

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UNiTED STATES PATENT Orrrcn.

CHARLES W. JEFFERSON, OF SOHENECTADY, NEW YORK, ASSIGNOR TO THE MICA INSULATOR COMPANY, A CORPORATION OF NEW JERSEY.

METHOD OF MAKING INSULATING MATERIAL;

SPECIFICATION forming part of Letters Patent No. 687,532, dated. November 26 1901.

Application filed February 7, 1901. Serial No. 46,306. (No model.)

T0 at whom it ntwy concern:

Be it known that 1, CHARLES W. J EFFER- SON, a subject of the Queen of Great Britain, and a resident of Schenectady, in the county of Schenectady and State of New York, have invented a new and Improved Method of Making Insulating Material, of which the following is a specification.

My invention relates to methods of manufacturing insulating material; and it has for its object the manufacture of such material that will not only be thoroughly flexible, pliable, and non-brittle, but that will also be able to resist a very high electrical voltage and to withstand a very great degree of heat.

Electrical insulators have been made in the shape of plates or sheets and of some comminuted or pulverized non-combustible insulating material mixed with ahardening cement. One of the disadvantages of this kind of insulator is that it is not pliable and that it is brittle and also that it has not the re: quired efficiency as to insulation and durability, and the plates or sheets so made being brittle and non-pliable are more apt to chip and break when being manipulated or cut into smaller pieces for insulation. In order to remedy these defects and to give the sheet more durability and flexibility, sheets of fabric have sometimes been introduced into the combined insulating sheet or plate; but the disadvantage of the use of such fabric is thatit is readily carbonized, and as soon as this happens the efficiency of the insulator is im paired. Sheets of insulating material have also been made from layers of scales of mica cemented by a varnish and then the sheet so formed dried by steam and then subjected to intense pressure, so thatthe varnish between the mica scales and between the layers will be expelled,leaving only sufficient of the varnish to cause the mica scales to adhere together; The plate or sheet so formed is then subjected to intense pressure, so that the diiferent layers of mica scales are formed into a compact sheet in a hard state. A sheet of insulation constructed as above described makes a very good insulator; but as the sheet itself is virtually composed of a solid mass of mica it is somewhat brittle and not as pliable as is sometimes desired. Also with such a construction of insulating-sheet it is liable to crack, especially when out into smaller pieces or trimmed. By my invention a very simple, inexpensive, pliable, non-brittle, and highly-efficient insulating material can be constructed.

My invention consists of the method herein described, and the accompanying drawings illustrate an embodiment of my improved method, in which Figure 1 illustrates in perspective a sheet of insulating material made in accordance with my improved method, said sheet being broken away at different parts to clearly show the construction. Fig. 2 is a fragmentary view, enlarged, in plan and showing how the different scales of mica may be laid and are united. Fig. 3 is a fragmentary crosssection, greatly magnified, of a portion of an insulating-sheet made in accordance with my invention. Fig. 4 is a similar view to Fig. 1, but showing a slightly-modified form of insulated sheet. Fig. 5 illustrates the mechanism which may be used in one stage of the process of making the insulating-sheet.

Similar numbers represent like parts in all the figures.

1 represents the pliable substance forming the body of my improved insulating-sheet and also arranged in alternate layers.

2 represents layers formed of mica scales 3, said layers 2 being united by the substance 1 and the spaces between the scales 3 and the layers 2 being filled in with said substance.

4 represents the flexible composition cover or coating of the insulated sheet.

5, Fig. 4, represents sheets of tissue-paper or other flexible porous material saturated with an insulating compound and forming 0 part of the sheet and interposed between the outer layer 1 and the coating or cover 4.

6 represents a body-plate of a table 7, which plate may be heated or cooled by means of a pipe 8 passing under said plate;

9 is a light roller to be used in pressing down the different layers of the sheet during the process of manufacture and for expelling gas from the same.

sulating material in a fluid or semifluid state is first applied to a baseplate 6, said plate having previously been coated with soapstone or some similar material, so that after said layer has become hardened, or partly so, it maybe readily scaled from the plate. The material which I prefer to use is an oxidized oil, and preferably oxidized linseed-oil, as such oxidized oil forms in itself a very good insulator and is quite pliable when oxidized or dried. In order to produce the best results, I take linseed-oil which has first been dxidized and then dissolve it with benzin or some similar solvent. Then I prefer to add to this dissolved oxidized oil a very small proportion of some gum, as copal-gum. This gives the oil a little more of an adhesive quality and a little more body. After the liquid above described isapplied in a'layer 1 to the baseplate 6, as above stated, a layer 2 of mica scales 3 is laid on the layer 1 of said liquid, preferably overlapping each other, then another layer 1 of the liquid is applied over the layer of mica scales, and this process is continued until the sheet is of the desired thickness, said sheet being made of alternate layers 1 of the insulating liquid, semiliquid or plastic, and of mica scales 3. When the sheet is of the desired thickness, the plate 6 is then heated, preferably by steam from a pipe 8. The highly-volatile quality of the benzin or other solvent will have caused it to evaporate to some extent even before the plate is heated, thus turning the oil or other liquid into a gum, uniting the different mica scales and layers of the same. The heat from the plate will cause still more evaporation of the solvent and tend .to dry the oxidized oil. Duringsaid evaporation and drying, while the sheet is still upon the plate, alight pressure is applied to the sheet by means of a roller 9 or' other device, such pressure being sufficient to smooth and level the layers of oxidized oil and mica scales and to expel the gas from the sheet; but such pressure must not be sufficient to squeeze out the oil or other binding compound, as such oil, which is now transformed into agum,is to constitute the main portion or body 1 of the insulatingsheet. The sheet is then put in an oven for a short time and dried. It is then taken out of the oven and coated by dipping or otherwise in the dissolved oxidized oil or other liquid, thus forming a coating or cover 4 .to the sheet, and then hung up in the oven-say with atemperature of about 100 Fahrenheitfor about two hours, with a heat gradually in creasing to about 400 Fahrenheit. The temperature of the oven is then gradually reduced for about two hours to about the degree of 'heat that the plate first became subjected to, which might be in the neighborhood of 100 Fahrenheit. The oxidized sheet (see Fig. 1) is now complete, and it is of a very pliable character, with the oxidized and baked oil 1 forming the main part or body of the sheet filling in all the spaces between the mica scales 3 and between the layers of the same and uniting said scales and layers, so that the completed sheet is formed in one solid mass.

Although I prefer to bake the sheet, as above stated, to procure the best results, such sheet may be dried in any other appropriate manner.

The scales of mica that I prefer to use in the manufacture of my new insulating material are such elementary or primary scales as are understood in mineralogy as being the thinnest sheets or single layers of mica that can be practically obtained by the continued process of cleavage or splitting. The object of forming the insulating material of such thin elementary scales is to prevent all liability of the different pieces of mica splitting, which thescales might do if they were thicker, and thus cause the splitting or separation of different parts of the insulating material, there being no oxidized oil or other adhesive substance between the separated layers of a double or multiple layered scale of mica. Even a partial separation of different parts of an insulator would leave a space for air and moisture, and thus impair the efliciency of the insulator. By reason of the use of a pliable adhesive insulating substance the finely-divided mica scales can be united in a solid mass with said substance, so that the resultant product is a sheet or body of very flexible and pliable insulating material that can be bent, doubled up, and twisted in any manner desired to suit the various forms and conditions for which insulators are used. If the adhesive substance that binds the mica scales together were not of a flexible and pliable nature, the completed insulating product could not be bent and twisted without liability of breaking.

The different layers of oxidized oil or other liquid may be applied with a brush or in any other appropriate manner, and the scales of the different layers should preferably overlap those of the other layers, so that the resist ance ofiered to an electrical current in an insulator so formed would be transverse to the surfaces of the mica scales, there being always, besides the oxidized insulating compound, a scale of mica to resist the force of the electrical current. may be attained by a second coating of the plate with dissolved oxidized oil, and it should then preferably be hung up in the oven in a reverse position to that in which it was suspended before. When this second baking is contemplated, it will not be necessary to keep the sheet in the oven quite as long the first time, (or it may be otherwise dried,) as the second baking will effect the desired result of thoroughly oxidizing and hardening the oil or body of the sheet and of uniting said body with the mica scales in a solid mass.

The insulating-sheet made by myimproved Still better results method has been found to be'most efficie'nt as an insulator, and it will Withstand a very high degree of heat and also a very high electrical voltage, higher than that of any compound insulating material so far known to me.

The insulating-sheet may be slightly modified in form by applying asheet 5 of thin porous material, '(see Fig, 4,) such as tissuepaper, to one or both of the outside layers 1' of the varnish previous to the drying and pressing stages of the process and then such covered or coated sheet dipped in the varnish and then baked in the oven, as above described. When this form of sheet is made, very small scales of mica may be used, and it will not be necessary to use as many layers of said scales as when the tissue-paper or other'fabric is omitted, as the layer or layers 5 of flexible material will form a durable binder for the entire sheet. The oxidized composition will thoroughly impregnate the tissue-paper or other fabric and render it virtually non-carbonizable. The efficiency of said sheet as an insulator is equal to that in which the coating of flexible fabric is omitted.

By practical experience I findthat the insulators made in accordance with my invention will resist at least fifteen hundred volts to one one-thousandth of an inch in thickness of said insulators.

What I claim as new, and desire to secure by Letters Patent,is--

1. Theimproved method of manufacturing insulating material, consisting of first applying a layer of mica scales to a layer of a pliable adhesive substance when in a liquid, semiliquid or plastic state, next applying a light-pressure to the sheet so formed sufficient to smooth out the layers and to expel the gas, but without squeezing out the adhesive substance and then drying said sheet, thereby forming a pliable insulating-sheet with the mica scales and adhesive substance united in a solid mass.

2. The improved method of manufacturing insulating material, consisting of first applying alternate layers of mica scales to alternate layers of a pliable adhesive substance when in a liquid, semiliquid or plastic state, next applying a light pressure to the sheet so formed sufficicnt to smooth out the layers and to expel the gas, but without squeezing out the adhesive substance and then drying the said sheet, thereby forming a pliable insulatingsheet with the mica scales and adhesive substance united in a solid mass.

3. The improved method of manufacturing insulating material, consisting of first applying a layer of mica scales to a layer of pliable adhesive substance when in the liquid, semiliquid or plastic state, next applying a light pressure to the sheet so formed sufficient to smooth out the layers and to expel the gas, but without squeezing out the adhesive sub-'- stance, next coating the sheet with said adhesive substance and then drying it, thereby forming a pliable insulating-sheet With the mica scales and adhesive substance united in a solid mass.

4. The improved method of manufacturing insulating material, consisting of first applying a layer of mica scales to a layer of a pliable adhesive substance in a liquid, semiliquid or plastic state, next applying a light pressure to the sheet so formed suflicient to smooth out the layers and to expel the gas, but without squeezing out the adhesive substance, next coating the sheets with said adhesive substance then drying it, and then baking it, thereby forming a pliable insulating-sheet with the mica scales and adhesive substance united in a solid mass.

5. The improved method of manufacturing insulating material, consisting in first applying a layer of mica scales to a layer of a pliable adhesive substance in a liquid, semiliquid or plastic state, next applying a light pressure to the sheet so formed suificient to smooth out the layers and to expel the gas, but Without squeezing out the adhesive substance, next coating the sheet with said adhesive substance then drying it, and then baking it, then coating said baked sheet with said liquid or semiliquid substance, then drying said coated sheet, thereby forming a pliable insulating-sheet with the mica scales and adhesive substance united in a solid mass.

6. The improved method of manufacturing insulating material, consisting in first applyingalayer of mica scales to alayer of a pliable adhesive substance in a liquid, semiliquid or plastic state, next coating the product so formed with said substance, next covering said coated product with alayer of a thin, porous, flexible material, next coating the product so formed with said liquid, semiliquid or plastic substance, then drying said combined product, thereby forming a flexible insulating-plate with the mica scales and adhesive substance united in a solid mass.

7. The improved method of manufacturing insulating material, consisting in first applying 'a layer of mica scales to a layer of a pliable adhesive substance in a liquid, semiliquid or plastic state, next coating the product so formed with said substance, next covering said coated product with a layer of thin, porous, flexible material,next applyinga light pressure to the sheet so formed sufficient to smooth out the layers and to expel the gas, but without squeezing out the adhesive substance, then drying said combined product, thereby forming a pliable insulating-plate with the mica scales, and adhesive substance and porous flexible material united in a solid mass.

8. The improved method of manufacturing insulating material, consisting in first applying a layer of mica scales to a layer of a liquid 'or semiliquid oxidized oil, next applying a light pressure to the sheet so formed sufiicient' to smooth out the layers and to expel the gas,"

but Without squeezing out said oil, and then drying said sheet, thereby forming a pliable insulating-sheet with the mica scales and adhesive substance united in a solid mass.

9. The improved method of manufacturing insulating material, consisting in first applying a layer of mica scales to a layer of a liquid orsemiliquid oxidized linseed-oil, next apply ing a light pressure to the sheet so formed sufficient to smooth out the layers and to expel the gas, but without squeezing out said oil, and then drying said sheet, thereby forming a pliable insulating-sheet with the mica scales and adhesive substance united in a solid mass.

10. The improved method of manufacturing insulating material, consisting in first applying a layer of mica scales to a layer of a pliable adhesive and oxidizable substance when in a liquid, semiliquid or plastic state, next applyinga light pressure to the sheet so formed sufficient to smooth out the layers and to expel the gas, but without squeezing out the adhesive substance, thereby forming a pliable insulating-plate with the mica scales and adhesive substance united in a solid mass.

11. The improved method of manufacturing insulating material, consisting in first applying a layer of overlapping mica scales to a layer of a pliable adhesive, and oxidizable substance when in a liquid, semiliquid or plastic state, next applying a light pressure to the sheet so formed sufficient to smooth out the layers and to expel the gas, but without squeezing out the adhesive substance,thereby forming a pliable insulating-plate with the mica scales and adhesive substance united in a solid mass.

12. The improved method of manufacturing insulating material, consisting in first applying alternate overlapping layers of mica scales to alternate overlapping layers of a pliable adhesive substance when in a liquid, semiliquid or plastic'state, next applying a light pressure to the sheet so formed sufficient to smooth out the overlapping layers and to expel the gas, but without squeezing out the adhesive substance, thereby forming a pliable insulating-sheet with the mica scales and adhesive substance united in a solid mass.

13. The improved method of manufacturing insulating material, consisting in first applying alternate overlapping layers of mica scales to alternate overlapping layers of a pliable, adhesive, and oxidizable substance when in a liquid, semiliquid or plastic state, next applying a light pressure to the sheet so formed sufficient to smooth out the overlapping layers and to expel the gas, but without squeezing out the adhesive substance, thereby forming a pliable insulating-sheet with the mica scales and adhesive substance united in asolid mass. 14. The improved method of manufacturing insulating material, consisting in first applying a layer of overlapping mica scales toa layer of a pliable adhesive, and oxidizable substance when in a liquid, semiliquid or plastic state, next applying a light pressure to the was sheet so formed sufiicient to smooth out the layers and to expel the gas, but without squeezing out the adhesive substance, next coating the sheet with said substance and then drying it, thereby forming a pliable insulating-plate with the mica scales and adhesive substance united in a solid mass.

15. The improved method of manufacturing insulating material, consisting in first applying alternate overlapping layers of mica scales to alternate overlapping layers of a pliable adhesive, and oxidizable substance when in a liquid, semiliquid or plastic state, next applying alight pressure to the sheet so formed sufficient to smooth out the overlapping layers and to expel the gas, but without squeezing out the adhesive substance, next coating the sheet with said substance and then baking it, thereby forming a pliable insulating-sheet with the mica scales and adhesive substance united in a solid mass.

16. The improved method of manufacturing insulating material, consisting in first applying a layer of mica scales to a layer of a liquid, semiliquid plastic insulating oxidized oil, next applying a light pressure to the sheet so formed sufficient to smooth out the layers and expel the gas, but without squeezing out the oil, next coating the sheet with said oil and then drying said sheet, thereby forming a pliable insulating-sheet with the mica scales and dried oxidized oil united in a solid mass.

17. Theimproved method of manufacturing insulating material, consisting in first applyin g alternate layers of mica scales to alternate layers of liquid, semiliquid or plastic insulating oxidized oil, next applying alight pressure to the sheet so formed sufficient to smooth out the alternate layers and expel the gas, but without squeezing out the oil, next coating the sheet with said oil and then drying said sheet, thereby forming a pliable insulatingsheet with the mica scales and dried oxidized oil united in a solid mass.

18. The improved method of manufacturing insulating material, consisting in first applying a layer of mica scales to a layer of a liquid, semiliquid insulating oxidized oil, next applying a light pressure to the sheet so formed sufficient to smooth out the layers and expel the gas, but without squeezing out the oil, next coating the sheet with said oil and then baking said sheet, thereby forming a pliable insulating sheet with the mica scales and baked oxidized oil united in a solid mass.

19. The improved method of manufacturing insulating material, consisting in first applying alternate layers of mica scales to alternate layers of a liquid, semiliquid insulating oxidized oil, next applying a light pressure to the sheet so formed sufiicient to smooth out the alternate layers and expel the gas, but without squeezing out the oil, next coating the sheet with said oil and then baking said sheet, thereby forming a pliablev insulatingsheet with the mica scales and baked oxidized oil united in a solid mass.

20. The improved method of manufacturing insulating material, consisting in first applying a layer of mica scales to a layer of aliquid, semiliquid or plastic adhesive, and oxidizable substance, next applying a light pressure to the sheet so formed sufficient to smooth out the layers and to expel the gas, but without squeezing out the adhesive substance, next coating the sheet with said substance and then drying it, then coating said dried sheet with said substance and then drying said coated sheet, thereby forming a pliable insulating-sheet With the mica scales and adhesive substance united in a solid mass.

21. Theimproved method of manufacturing insulating material, consisting in first applying a layer of mica scales to a layer of a liquid, semiliquid or plastic adhesive, and oxidizable substance,next coating the product so formed with said substance, next covering said coated product with a layer of a thin, porous flexible material, next coating the product so formed with said substance, then drying said combined product, thereby forming a pliable insulating-plate with the mica scales and adhesive substance, and porous flexible material united in a solid mass.

22. The improved method of manufacturing insulating material, consisting in first applying a layer of mica scales to a layer of a liquid, semiliquid or plastic adhesive, and oxidizable substance, next applying a light pressure to the sheet so formed suificient to smooth out the layers and to expel the gas, but without squeezing out the adhesive substance, next coating the sheet with said substance and then baking it, then coating said baked sheet with said substance and then baking said coated sheet, thereby forming apliable insulating-sheet with the mica scales and adhesive substance united in a solid mass.

23. The improved method of manufacturing insulating material, consisting in first applying a layer of mica scales to a layer of a liquid, semiliquid or plastic adhesive, and oxidizable substance, next coating the product so formed with said substance, next covering said coated product with a layer of a thin, porous flexible material, next coating the product so formed with said substance, then baking said combined product, thereby forming a pliable insulating-plate with the mica scales and adhesive substance, and porous flexible material united in a solid mass.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

CHARLES WV. JEFFERSON.

Witnesses:

ALLAN H. JACKSON, HOMER STRONG. 

